Apple has fixed a zero-day vulnerability in macOS exploited in the wild by Shlayer malware to bypass Apple’s File Quarantine, Gatekeeper, and Notarization security checks and download second-stage malicious payloads. Shlayer is a multi-stage trojan that attacked over 10% of all Macs, according to a Kaspersky report from January 2020. Users are now alerted that malicious apps “cannot be opened because the developer cannot be identified”” and advised to eject the mounted disk image because it may contain malware.”
Source: https://www.bleepingcomputer.com/news/security/apple-fixes-macos-zero-day-bug-exploited-by-shlayer-malware/